With the popularity of electronic devices such as smart mobile phones and touch screens, multi-functional smart watches or smart bands having a touch screen are available on the market. The smart watch or smart band includes a display device, and the display device includes at least one display screen. Various kinds of information, such as time, date, temperature, or user's physical status, may be displayed on an interface where the display screen is located. The smart watch or smart band may be worn on a user's wrist or arm by a fixing apparatus, and the fixing apparatus is connected to a frame on which the display device is mounted. The device has the following issue, when the smart watch or smart band has insufficient power and needs to be charged, or when it is required to use the display device separately, it is required to ensure that the smart watch or the smart band can keep working at the meantime, for example, keep displaying the information, such as time, date or the user's physical status, thus the fixing apparatus of the smart watch or smart band has to be fixed to the user's wrist or arm all along.